The present invention relates to the production of building materials and, more specifically, to cements and processes for producing the same.
Cements are known which contain highly-basic calcium silicate (alite), calcium ortho-silicate (belite), calcium chloroaluminate, calcium alumoferrite. In addition to the above-mentioned components, the cement might contain such additives as sulphates, nitrates, chlorides of alkali or alkali-earth metals.
A process for producing the above-mentioned cements is also known which comprises calcination of a raw mixture consisting of calcareous, silicaceous, aluminous, ferrous components and calcium halide at a temperature within the range of from 1,300.degree. to 1,400.degree. C., followed by grinding of the resulting cement clinker. At the grinding stage the clinker might be added with such agents as sulphates, nitrates, chlorides of alkali or alkali-earth metals.
The prior art cements, especially those with a high aluminate content have highly exothermal characteristics at the initial stage of the hydration process, which causes certain difficulties in laying big concrete monoliths based on such cements and impairs their quality. Furthermore, such prior art cements have an insufficiently high activity which hinders application thereof for the production of high-strength concretes.
The above-described prior art process for producing such cements has the disadvantage of a high calcination temperature, resulting in an increased consumption of fuel. Furthermore, the cement clinker produced at this temperature features a lowered grindability which results in a high power consumption for the grinding thereof.